Machine for severing a ribbon of plasterboard to form plasterboard panels and finishing the ends of the panels



July 5, 1955 G. A. B U'ITRESS 2,712,169

MA NE FOR SEVERING A RIBBON PLASTERB D FORM PLASTERBOARD PANELS FINISH THE ENDS OF THE PANELS Filed Aug. 5, 1951 2 Sheets-Shem l iififij ifi'Tl July 5, 1955 G. A. BUTTRESS MACHINE FOR SEVERING A RIBBON 0F PLASTERB TO FORM PLASTERBOARD PANELS AND FINISHI ns OF THE EN THE PANELS Filed Aug. 3, 1951 2 Sheets-Sheet 2 gg'geui Bu fgres 5 United States Patent 0 IVEACHINE FDR SEVERINE A REP-EON 0F PLAS- TERBOARD TO FL'RM PLASTERBQARD PANELS AND FINISHING THE ENDS OF THE PANELS serge A. Buttress, Los Angeles, Calif.

Application August 3, 1951, Serial No. 240,241

6 Claims. (ill. 25-1fi7) This invention relates to a cut-off mechanism for use in the manufacture of plasterboard panels in severing a ribbon of newly formed plasterboard to form panels therefrom of predetermined lengths.

The primary object of the invention is to provide a cutofi mechanism of the above character which is adapted to 2 seal the severed ends of the plasterboard coincident with severance thereof by bringing together at .the point of cutoif the severed ends of paper or cardboard facing sheets with which the plasterboard is equipped; the mechanism being capable of finishing end edges of plasterboard at least substantially in accordance with the method set forth in Letters Patent of the United States Number 2,523,861 issued to me under date of September 26, 1950.

As set forth in the patent aforesaid this invention relates to plasterboard of the type wherein a sheet-like body of filler of hardened plastic material is faced with cardboard of similar sheets to produce a board for use as a base for plaster on walls and ceilings or as sheeting in finishing walls and ceilings, and more particularly pertains to the finishing of such board so that critical margins of the plastic sheet-like body are covered by the facing sheets and the board is given a particular shape and finished appearance along margins thereof to provide advantages which will be hereinafter pointed out.

In the manufacture of plasterboard, paper, cardboard, or like facing sheets are fed in long strips over a table or on a conveyor while a soft and Wet plastic material is applied therebetween whereby a long ribbon of plasterboard stock may be formed subject to being cut into desired lengths while the plastic material is wet. Later methods provide for bending or folding the facing sheets around the longitudinal edges of the long strip of stock board during the forming thereof so that the plasterboard lengths cut from the strip will have opposite side edges thereof in finished and protected form with the plastic body sheet covered along said edges by the cardboard facing sheets. However, in so far as I am aware other than is disclosed in the patent aforesaid, the transverse edges of these board lengths are square, expose the dry plastic filler and present an unfinished appearance. Exposure of the dry plastic body sheet in this manner is objectionable in that when plaster is applied over a number of such boards on a wall or ceiling, the exposed edges of the dry plastic body sheet will absorb moisture from the applied plaster at the joints of said boards and weaken the plaster at the most critical points, namely, the joints in the base formed by the boards, thereby impairing the monolithic characteristic of the body of applied plaster and often causing cracking and discoloration thereof. Moreover, these ordinary square-cut edges of the board when opposed in an assembly of plaster boards on a wall or ceiling do not afford an effective keying of the applied plaster and present an unfinished appearance especially when the boards are used as finishing sheeting on walls and ceilings.

It is the primary object of this invention to provide an apparatus for producing finished cardboard-covered edges 2,712,169 Patented July 5, 1955 2. of board lengths of plasterboard of the character described, incident to the severing of such lengths from a long strip of the plastic board stock with the edges produced by such severing given a particular shape and treatment to facilitate the keying of plaster applied to a plu-. rality of the boards, give the board a finished appearance, and reinforce and add to the strength thereto.

Another object of this invention is to provide a means for finishing plasterboard of the character described while the cardboard facing sheets and the. plastic filler thereof are yet wet and before the setting of the latter, which consists in first applying to the facing sheets along a line extending across both sides of the board, a pressure such that the plastic filler will be laterally displaced and the facing sheets forced inwardly and caused to form grooves and to abut one another along the bottom of said grooves, and then forcibly continuing the pressure in such manner that the abutting portions of the facing sheets are severed, whereby successive applications of the aforesaid pressures a at spaced points along the plasterboard stock will produce desired lengths of plasterboard each having the plastic body along the severed edges covered by the abutting portionsof the facing sheets and being given a predetermined beveled? or tapered form at such edges.

Another object is to provide a finishing apparatus for plasterboard wherein opposed dies are first presesd against opposite sides of the wet unhardened stock length of plasterboardto form transverse grooves in oppositefsides of the board Withthe cardboard facing sheets forced into abutting relation to one another along the bottoms of said grooves, and then forcibly moving one of the dies toward the other so as to sever the facing sheets along the abutting portions thereof whereby the resultant edges are sealed by said abutting portions. of such sheets and are beveled on opposite sides and given a finished appearance.

Another object is to provide a construction in the dies whereby the portions of the facing sheets bent over the severed ends-of the plastic body and brought into abutting relation to each other are subjected to a scoring or rupturing action at the point. of the initial bend of the facing sheets so as ,to break or rupture fibers of the facing sheets at such point and thereby insure againstthe bent or curved portions of the facingsheet from becoming separated at their abutting edges under the urge of an inherent tension in the facing sheets tending to cause the bent end port-ions thereof to return toward normal on being relieved of pressure of the. dies and which is particularly apt to occur during subsequent drying of the finished plasterboard panels.

' Where the facing sheets of the plasterboard ribbon are brought into overlying relation to each other on one side of the board to close the longitudinal margins of the board'with a marginal portion of one of the facing sheets bent around the edge thereof, a double thickness of the facing sheets will result adjacent the opposite margins of underlying layer or portion of the other facing sheet will be perforated so that portions of the soft wet plastic material will be caused during the pinching oil operation to be squeezed into the cut formed in the overlapping pertions' of the facing sheet to seal such cut and cause the margins thereof to adhere to each other and to the underlying facing sheet layer. I

A further object is to provide a construction in the machine whereby the severance of the plasterboard ribbon may be effected while the ribbon is advancing.

With the foregoing objects in view together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the combination, construction and arrangement of parts hereinafter described and claimed, and illustrated by way of example in the accompanying drawings, in which:

Fig. l is a view in section and elevation of the machine with parts broken away showing the mechanism in readiness for operation:

Fig. 2 is a view in cross section and elevation as seen on the line 22 of Fig. l:

Fig. 3 is a detail in perspective and section taken on the line 3-3 of Fig. 2 illustrating the construction of the tary portion of a plasterboard showing: the manner of sealing the ends thereof in the operation shown in Fig. 5: Fig. 7 is a plan view of the mechanism shown in Fig. 1: Fig. 8 is a view in cross section taken on the line 88 of Fig. 7 of the plasterboard ribbon being fed to the machine:

Fig. 9 is a view in elevation partly in section with portions broken away showing the die members as positioned astride the plasterboard ribbon preliminary to effecting severance thereof:

Fig. 10 is a detail in perspective illustrating a modified form of the die members: and

Fig. 11 is an enlarged detail in section of the pinching off edges of the die members and depicting a preferred form of the contouring thereof.

Referring to the drawings more specifically A indicates generally a plasterboard which embodies a layer of plaster a interposed between upper and lower facing sheets b and c formed of paper, cardboard or the like. As here shown the lower facing sheet 0 is extended around the side margins of the plaster body a and has its longitudinal edges d overlapped on and adhered by a suitable adhesive to the longitudinal margins e of the upper facing sheet b.

In the manufacture of the plasterboard as commonly practiced wet plastic material for forming the plaster layer a is imposed upon an advancing lower facing sheet 0 and spread thereon in a substantially uniform layer whereupon the upper facing sheet b is applied to the plastic layer in a continuous advancing strip and the margins of the lower facing sheet are turned around and over the side margins of the plaster layer and adhered to the margins of the upper facing sheet; the assembly being advanced on a conveyor belt and subjected to the action of rollers so as to produce an advancing ribbon of plasterboard of uniform thickness to be subsequently cut into panels of predetermined lengths, which in this instance is effected by mechanism constituting the present invention.

This mechanism, as particularly shown in Figs. 1, 2 and 7, embodies a carriage B including a bed-plate 14 the ends of which are fixedly supported on end frames 15-15 fitted with pairs of rollers 16--16 supported upon and adapted to traverse spaced rails 17-17 here shown as constituting the side rails of a roller conveyor C on which the plasterboard A is conveyed to and from a cut-off mechanism D mounted on the carriage B. The conveyor C embodies a series of spaced horizontal rollers 18 revolubly supported on the side rails 17-17 on which the ribbon of plasterboard A is advanced to the carriage as particularly shown in Fig. 7, and also embodies a series of horizontal rollers 19 mounted on the rails 1717 for carrying away the plasterboard panels severed from the plasterboard ribbon by the cut-off mechanism D. A gap is afforded between an end roller of the series of rollers 18 and an end roller of the series of rollers 19 to afford a space between the ribbon feeding rollers 18 and the panel discharging rollers 19 to permit short back and forth travel of the carriage B on the rails 1717. Rearward movement of the carriage B is limited by stops 2020 on the rails 1717 against which the rear ends of the carriage side frames 15-15 are adapted to abut as shown in Fig. 7.

The bed-plate 14 extends on a plane slightly below the plane of the uppermost peripheral portions of the rollers 1819 and mounted and projecting above the upper side of the bed-plate is a fixed die member 21 extending longitudinally of the bed-plate 14 and transversely of the carriage B; the die member 21 being designed to cooperate with a vertically moveable die member 22 mounted on the carriage B to effect severance of the plasterboard ribbon as will presently be described. The die member 22 is mounted on the lower ends of a pair of stems 23 extending through and reciprocally guided in openings 24 formed in a horizontal cross bar 25 extending in superimposed spaced parallel relation to the bed-plate 14 and rigidly supported at its ends on standards 26-26 erected on the end portions of the bed-plate 14. Springs 27 wound around the stems 23 bear between the upper face of the cross bar 25 and abutments 28 on the stems 23; the springs 27 being tensioned to normally maintain the stems 23 and the die member 22 thereon in an uppermost position with the die member 22 abutting the under side of the cross bar 25 and disposed in spaced relation to the die member 21 as shown in Fig. 1.

The ribbon of plasterboard A is designed to be fed be tween the die members 21 and 22 when in their spaced apart position and the die member 22 is designed to be depressed into meeting engagement with the die member 21 to effect severance of the plasterboard interposed therebetween and also seal the severed ends of the plasterboard as will be later described.

Means are provided on the carriage B for directing the plasterboard ribbon between the die members 21 and 22 which is adapted to yieldably support the portion of the plasterboard ribbon leaving the end roller 18 in a slightly elevated position relative to said roller so as to feed the ribbon through the carriage B in a slightly elevated position relative to the die member 21 and yet permit depression of the portion of the plasterboard ribbon extending through the carriage during the severing I operation. This means is here shown as comprising a panel 29 extending between the rear portions of the carn'age side frames 1515 and overlying the bed-plate 14. The panel 29 is pivotally supported at its ends adjacent its rear margin on pivots 39-30 connecting with brackets 3131 on the carriage side frames. The for ward end portion of the panel 29 is supported on springs 32 hearing on the bedplate 14 which springs normally support the panel 29 with its forward edge disposed on a plane slightly above the upper margin of the die member 21; the springs being sufficiently strong to maintain the forward marginal portion of the panel 29 in this elevated position under the load of plasterboard imposed thereon and being fed thereto from the rollers 18.

The die members 21 and 22 are of such length as to extend completely across the plasterboard interposed therebetween; the die members 21-22 embodying respectively blunt edged blade portions f and g presented toward each other in vertical and longitudinal alignment. The blade edge 1 of die member 21 is transversely fiat while the blade edge g of the die member 22 is rounded or convex as particularly shown in Fig. 11 so that such edges 1 and g will effect a pinching off action rather than a cutting action as in the case of sharp knife edges so that when the blade edges are brought to bear under pressure against the facing sheets I; and c on opposite sides of the plasterboard the facing sheets will be pressed inwardly toward each other through the then wet and soft plaster body a until they are in abutting relation with each other at a point intermediate the thickness of the plasterboard and then be severed by pinching action of the blade edges 1 and g on bringing such edges together.

Each of the die members 21 and 22 is formed with concaved faces h leading from opposite sides of the blade edges 1 and g which faces in cross section are preferably formed on 90 degree arcs of circles having a radius at least substantially corresponding to one-half the mean thickness of the plasterboard whereby in effecting the pinching-off operation the die members will act to bend the end portions of the facing sheets adjacent the point of severance thereof on a convex curvature so as to impart a rounded contour to the severed ends of the plasterboard.

As a means for insuring against the curved or bent portions of the facing sheets from separating from the plaster body a and tending to straighten out after being disengaged from the die members, each of said members is provided on the opposite sides thereof with scoring blades having edges j projecting from the base margins of the convex faces h with the scoring blade edges j on the die member 21 presented toward those on the die member 22 in vertical alignment therewith; the edges j being designed to at least partly penetrate the facing sheets so as to break, rupture, or weaken at least a major portion of the fibers of the facing sheet along the point of initial bending of the end portions thereof, and sufiicient to render the facing sheet at least substantially inert along the lines of contact of the scoring blades 1'. it is desirable in most instances to form the blade edges j with minute teeth or serrations as particularly shown in Fig. 3, but in some cases straight knife like edges may be employed as shown in Fig. 10.

As a means for insuring the severance or breaking of the fibers of the double thickness of the marginal portions (1 and e of the facing sheets the scoring blades of the upper die member 22 are formed at the end portions thereof overlying the side marginal portions of the plasterboard with an increased extent of projection as indicated at k which extended portion may be in the nature of teeth. as shown in Fig. 9 or straight edged as shown in Fig. 10.

As a means for actuating the die member 22 a rockshaft 33 is journalled on the standards 26--26 to extend above and to one side of the cross bar and mounted on the rock-shaft 33 are fingers 34 which overlie the upper ends of the stems 23. Fixed on one end of the rock-shaft 33 is a lever 35 here shown as being ar ranged so that on being depressed, downward movement of the fingers 34 and stems 23 to depress the die member 22 will be effected.

A pull spring 36 connects with the base portion of one of the standards 26 and with a fixed arm 37 formed the inner end of the lever 35, which spring exerts a downward pull on the arm 37 to position the latter against a stop 38 and normally hold the lever 35 in an elevated position and to restore the lever to such position on release thereof after being depressed.

In the operation of the invention the ribbon of plasterboard A is delivered continuously over the conveyor rollers 18 and tiltable plate 29 between the die members 21 and 22 and onto the conveyor rollers 19. Initially the carriage B is disposed in its retracted position against the abutments 2:) as shown in Fig. 1. When it is desired to eifect severance of the plasterboard ribbon the lever 35 is depressed to cause the upper die member 22 to bear on and depress the plasterboard ribbon and cause the blade edges 1 and g of the die members to effect their pinching oif action and to simultaneously cause the contoured forming faces h, and the scoring blades j of the die members to coact in sealing the several ends of the plasterboard by bending the end portions of the facing sheets thereover as before described, and as indicated in Fig. 5. As before stated, the bending of the facing sheets by the contoured faces h of the die members 2021 is accompanied by scoring or puncturing the facing sheets along the line of initial bend thereof as indicated at i in Fig.6 by :the blades j so as to at least substantially negative resiliency of the facing sheets along such lines, and'where the facing sheets are perforated or slit by the blades j to cause portions of the wet plaster body a to be squeezed into openings along such lines, the curved portions of the facing sheets will be prevented from subsequently separating from the plaster body a under inherent tension of the facing sheets. The curved portions of the facing sheets will thus lie inert in close and tightly adhered contact with the formed ends of the plasterboard panels with the abutting edges of the facing sheets securely adhered together.

During this pinching-off and sealing operation, which is very rapidly effected, the pivoted and spring supported plate 29 is moved downwardly under the pressure imposed on the plasterboard by the die member 22 to permit downward advance of the lower half of the plasterboard interposed between the die members to move astride the die member 21 while the die member 22 is advancing into the upper half of the plasterboard. During this time the carriage B will be advanced a short distance under the urge of the advancing ribbon of plasterboard engaging the die members 21 and 22. immediately upon completion of the severing operation the lever 35 is restored to its normal elevated position whereupon the springs 27 restore the die member 22 to its elevated position and the springs 32 elevate panel 29 and thereby elevate the severed end portion of the plasterboard ribbon to permit it to pass freely between the die members. 21 and 22 whereupon the carriage B is moved back to its rearwardmost position and the machine placed in readiness for another operation.

It will be seenfrom the foregoing that panel lengths of the plasterboard may be formed from the ribbon thereof of any suitable lengths with the trailing end of the severed panel and the leading end of the advancing ribbon effectively sealed by the facing sheets as particularly shown in Figs. 5 and 6.

As before stated the severing operation'is effected while the plaster body a of the plasterboard is wet and soft or not completely set so that the portions of the plaster body interposed between the-die members 21 and 22 will be compressed by the latter whereby the plaster along the severed end edges of the panels will be rendered more compact and thereby strengthened. This with the rein-- forcement afforded by the rounded end portions of the facing sheet overlying the plaster body at the ends of the panels considerably strengthens such end edges against breakage during handling of the panels as well as sealing in the plaster body a and imparting a shape to the end edges of the panels affording a better keying action when plaster is applied to the board when employed in the construction of plaster finished walls and ceilings.

In the construction here shown actuation of thelever 35-to depress the die member 22 and retraction of the carriage B to its initial or starting position is effected manually. It will be understood however that these operations may be elfected automatically by the employment of conventional mechanism commonly employed in plasterboard cut-ofi machines and not necessary to be here shown.

It is to be noted that by the construction and mode of operation of the die members herein set forth the inturned severed end portions of the facing sheet will be tightly impressed in abutting relation along their severed margins and will be retained in place by adhesion to the plaster body a.

The finished panels after leaving the cut-off mechanism are advanced on the conveyor rollers 19 to a point of discharge where the plaster body a is permitted to completely set after which the plasterboard panels are kiln dried preparatory to packaging and shipment for use.

While I have shown and described a specific embodiment of my invention I do not limit myself to the exact details of construction set forth, and the invention embraces such changes, modifications and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

I claim:

1. In a machine for severing a ribbon of plasterboard of the type embodying a plaster layer interposed between paper facing sheets to form plasterboard panels and finishing the ends of the panels at the stage of manufacture thereof when the plaster layer is soft and wet and the facing sheets are moist, a horizontally moveable carriage, a bed-plate fixed on said carriage, an upwardly presented die member fixed on said carriage and projecting thereabove, spring supported depressible means on said carriage for directing a plasterboard ribbon up and over said die member, a vertically moveable die member on said carriage presented downwardly toward said first named die member, said die members having opposed pinchoif blade edges of a length to extend across a plasterboard ribbon, spring means for normally maintaining the vertically moveable die member in its uppermost position, means for depressing said moveable die member to bring the pinch-off blade edges of the die members together; said die members each having arcuate concave faces on opposite sides of the blade edges thereof engageable with the facing sheets on the ends of a plasterboard when severed by said blade edges to seal the ends of the plasterboard with portions of said facing sheet.

2. In a machine for severing a ribbon of plasterboard of the type embodying a plaster layer interposed between paper facing sheets to form plasterboard panels and finishing the ends of the panels at the stage of manufacture thereof when the plaster layer is soft and wet and the facing sheets are moist, a horizontally moveable carriage, a bed-plate fixed on said carriage, an upwardly presented die member fixed on said carriage, spring supported depressible means on said carriage for directing a plasterboard ribbon over said die member, a vertically moveable die member on said carriage presented downwardly toward said first named die member, said die members having opposed pinch-off blade edges of a length to extend across a plasterboard ribbon, means for normally maintaining the vertically movable die member in its uppermost position, means for depressing said moveable die member to bring the pinch-off blade edges of the die members together; said die members each having arcuate concave faces on opposite sides of the blade edges thereof engageable with the facing sheets on the ends of a plasterboard when severed by said blade edges to seal the ends of the plasterboard, and scoring blades on the opposite sides of each of said die members with the edges of the blades on one of the die members presented toward the edges of the blades on the other die member.

3. The structure called for in claim 2 in which the edges of said scoring blades are toothed.

4. The structure called for in claim 2 in which the 3 edges of said scoring blades on at least one of said die members include at each end thereof a series of elongated fiber severing teeth projecting beyond the intermediate edge portions of the scoring blades.

5. In a machine for severing a ribbon of plasterboard of the type embodying a layer of plaster interposed between and covered by paper facing sheets to form plasterboard panels and finishing the ends of the panels at a stage in the manufacture thereof when the plaster layer is soft and wet and the facing sheets are moist, a

plasterboard ribbon conveyor, a reciprocable carriage arranged in said conveyor and moveablein the direction of the length thereof, a bed-plate embodied in said carriage, a fixed upstanding die member on said bedplate having an upwardly projected pinch-01f blade, a

panel hingedly mounted on said carriage to swing vertically and having its hinged portion presented to said conveyor and having a free end overlying said bed-plate, springs yieldably supporting the free end portion of said panel to normally dispose the free end thereof on a plane above the pinch-off edge of said blade, a vertically reciprocable die member on said carriage having a downwardly presented blade formed with a pinch-01f edge opposing the pinch-01f edge of the fixed die member, spring means for normally maintaining said moveable die member in an elevated position in spaced reiation to the fixed die member, and means for advancing said moveable die member in opposition to said spring means to etfect severance of the plasterboard ribbon extended over said fixed die member.

6. in a machine for severing a ribbon of plasterboard of the type embodying a layer of plaster interposed between and covered by paper facing sheets to form plasterboard panels in finishing the ends of the panels at a stage in the manufacture thereof when the plaster layer is soft and wet and the facing sheets are moist, a pair of superimposed die members having opposed blades formed with pinch-off edges and convex molding and paper pressing faces on opposite sides of said blades, and paper rupturing blades on opposite sides of said die members at the base of said curved faces with the edges of the rupturing blades on one of the die members aligned with the edges of the rupturing blades on the other die member, and means for actuating one of said die members relative to the other.

References (Iited in the file of this patent UNETED STATES PATENTS 309,568 Schlickeysen Dec. 23, 1884 1,698,351 Storey Jan. 8, 1929 1,754,429 Knode Apr. 15, 1930 1,811,412 Whitacre June 23, 1931 1,874,922 Delaney Aug. 30, 1932 1,973,092 Mooney Sept. 11, 1934 2,523,861 Buttress 2. Sept. 26, 1950 2,589,022 Page Mar. 11, 1952 FOREIGN PATENTS 440,064 Great Britain Dec. 19, 1935 

